This invention relates to a cover structure. It relates further to preferred methods of employ of such cover structure.
Known for employ in horticulture are hotbed covers consisting of a metal carrier frame covered by a flexible plastic sheet. The erection of such hotbed covers is rather fastidious, requiring the plastic sheet to be fastened separately. In addition, their range of employ is rather restricted, as their shape is rigidly determined by the shape of the carrier frame. These hotbed covers are moreover not particularly durable, as the plastic sheet is supported by the carrier frame only at widely spaced intervals.
In the construction of water retaining structures such as dams and the like it is also known to cover the dam core flanks with a simple plastic sheet serving as a sealing layer. The plastic sheet is usually supplied in the form of wound rolls and applied to the embankment in the form of continuous overlapping webs. Subsequently a covering layer is applied over the sheeting in order to protect it and to retain it on the embankment. In this method it has to be considered disadvantageous, however, that the sheeting tends to slip due to the slope of the embankment or under the influence of wind. A further disadvantage is to be seen in the fact that the sheeting is easily damaged by stones contained in the material of the core or the covering layer, whereby its function as a sealing layer is defeated.